The present invention relates to a control cable, and more particularly, to a control cable having noticeable flexibility, load efficiency and stroke efficiency.
In conventional manually operated parking brakes, a rod-link mechanism or a chain transmitting mechanism have been used as a remote control means.
On the other hand, a control cable which has a specified construction shown in FIGS. 5 and 6 has been employed in a special technical field, e.g. for subway vehicles, where saving space and light weight are strongly requested.
The control cable shown in FIGS. 5 and 6 is a so-called ball-bearing-type control cable. The control cable comprises a flat belt-like center race 21 with concave grooves extending in the longitudinal direction, a number of steel balls 22 arranged with the same intervals at the upper and lower sides of the center race 21, retainers for keeping intervals of the balls 22, a spiral tube 25 surrounding the outer races 24 and an outer coat 26, etc. In this type of control cable, the center race 21 is a movable member, and the balls 22 and the retainers 23 move also by a half stroke of the center race 21 in order to reduce the frictional resistance.
The above-described conventional ball-bearing-type control cable has problems that the use is limited. That is to say, it is difficult to arrange the control cable in three-dimensional form or in a twisted arrangement, and is low in flexibility, since the shape of the center race 21 as a movable member is flat. And the stroke of the inner race is restricted, since a space for allowing the linear motion of the retainers is required.
For example, when the control cable is arranged in a three-dimensional form or U-shaped form, the balls tend to be biased to one-side as the center race reciprocally slides, since resistances of the balls are different from each other between the upper and lower sides with respect to the center race 21. Therefore, there is a risk that the effect of ball-bearing (rolling contact) will finally disappear, and gallings will happen in the center race 21 and the balls 22, and then, operation becomes down.
The object of the present invention is to provide a control cable having a slidable inner cable and a conduit and having the same load efficiency (rare (%) of an output force W obtained from the other end of a cable to an input force F applied to an end of the cable) and the same stroke efficiency (rate (%) of an output stroke of the other end of the cable to an input operation stroke (including stroke loss)) as the above-mentioned ball-bearing-type of control cable, and further, which can be easily arranged in three-dimensional form.